Morphology, mechanical, and water transport properties of melt blended EVOH/PVOH films

ABSTRACT Herein, we report for the first time the successful preparation of ethylene–vinyl alcohol (EVOH)/poly(vinyl alcohol) (PVOH) blends by a melt blending process for PVOH volume content ranging from 0 to 30%. Thermal stability up to 270 °C was maintained for all blends. The blends morphology consisted in spherical low size PVOH domains homogeneously dispersed in the EVOH matrix with good interfacial properties. An increase of the mean size of the PVOH domains (from 0.3 to 1.2 μm) and of the size distribution was evidenced as the PVOH content increased. The contribution of each phase to the water sorption and diffusion was clearly demonstrated. The impact of water uptake was investigated on the chains mobility by using Gordon–Taylor law and on the mechanical properties of the blends with respect to the reference polymers. It was pointed out that the reinforcing effect of PVOH phase decreased as the water activity increased. However, a significant elongation at break was maintained, underlining the major role played by the EVOH continuous phase at high water activity. Finally, it was shown that adding PVOH to EVOH up to 15 vol % allowed strengthening the material at low water activity and keeping interesting elongation at break and barrier properties at high water activity. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57 , 838–850